Pneumatic temperature-responsive apparatus



April 17, v1951 D. w. MOORE, JR., x-:TAL 2,549,622

PNEUMATIC TEMPERATURE-RESPONSIVE APPARATUS Filed Jan. 24, 1947 suCT|oN PUMP I COMPRESSOR j fagu N v "VI/II 'e t E 2 uw gr E L9 *+A E N l i, V E l -E i l' Q I LL l Il E@ l Il O e .2l E

N N INVENTORS 9 g M -DAvlD w, MooRE,Jr.

2 BYAL ED G.NAsH

Patented Apr. 17, 1951 PNEUMATIC TEMPERATURE-RESPONSIVE APPARATUS David W. Moore, Jr., New York, and Alfred G. Nash, Garden City, N. Y., assignors to Fairchild Camera and Instrument Corporation, a corporation of Delaware Application January 24, 1947, Serial No. 724,142

'Il-his invention relates to pneumatic tempera.- ture-responsive apparatus and, while it is of general application, it is particularly adapted to the measurement of temperature of an elastic fluid at a temperature so high that ordinary temperature measuring apparatus is inapplicable, as, foriexample, to the measurement of the temperature of combustion gases in an internal com- PV=RT (1) where I- Pi=fabsolute pressure of the gas V'=volume of the gas T=temperature of the y gas R=the gas constant In the system of that application, a quantity of high-temperature elastic iiuid is extracted from its container, cooled, and its mass flow measured, regulated, or otherwise determined and it is Ashown that the volumetric flow vof the hot gas through a metering orifice, as determined by the differential pressure across such orifice, is representative of a temperature factor ofthe hot fluid.` If the high-side orifice pressure is maintained constant, such differential pressure is Yrepresentative of the actual temperature of the fluid on avproperly calibrated scale.

The present invention constitutes an rimprove- 4ment on the temperature-responsive apparatus `rif-aforesaid l:Lo-pending application and comprises essentially a simplification of the apparatus for determining they fluid mass iiow of the extracted uid. This simplified apparatus utito the valve to maintain the differential pressure -across the controlling constriction substantially lizes direct-acting condition-responsive.elements in lieu of the electrical servo mechanisms of aforesaid copending application.

The present invention also comprises certain modifications of the apparatus of the aforesaid application to adapt it for application to hightemperature low-pressure elastic uids at static.

pressures insufficient to maintain adequate differential pressures across the metering and controlling constrictions of ,the apparatus.

t is an object of the present invention, therefore, to provide a new and improved pneumatic temperature-responsive apparatus of simple, economical, and rugged construction.

It is another object of the invention to provide a new and improved pneumatic temperature-responsive apparatus in which the controlling or regulating operations are effected by direct-acting mechanisms responsive to the several conditions, thus avoiding the necessity of auxiliary servo mechanisms.

It is another object of the invention to provide a new and improved pneumatic temperature-responsive apparatus which is suitable for response to high-temperature elastic fluids at static pressures insufficient to maintain adequate differential pressures across the metering and controlling constrictions.

In accordance with the invention, there is provided a pneumatic apparatus responsive to a temperature factor of an elastic uid in a container comprising a conduit adapted for fluid connection with the container, a metering constriction in the conduit, and a controlling constriction in the conduit. The apparatus also includes heat-exchanging means between the constrictions for modifying the temperature of the fluid, a valve inthe conduit, and a differential pressure-responsive means connected across the controlling constriction and connected directly with variations in thetemperature of the fluid 'at such constriction,

Further in accordance with the invention, there is provided a; pneumatic temperature-responsive apparatus of the type described, comprising a metering constriction in the fluid conduit, a controlling constriction in the conduit, means for inducing a flow of elastic fluid through the conduit to maintain substantial differential pressures acrossl such constrictions, heat-exchanging means between the constrictions for modifying the temperature of the fluid, and means responsive to the differential pressure across the controlling constriction for determining the fluid mass flow through the conduit. The apparatus also includes means responsive to the differential fluid pressure across the metering constriction for deriving an effect representative of a temperature factor of the contained iiuid.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

Referring to the drawing, Fig. 1 is an illustration, partially schematic, of a pneumatic temperature-responsive apparatus embodying the invention for measuring the ltemperature of a high-temperature gas under loW pressure, While Fig. 2 is a modified form of temperature-responsive apparatus also for measuring the temperature" of a high-temperature, low-pressure elastic uid in a container.

Referring now to Fig. 1 of the drawing, there is represented a pneumatic apparatus responsive to Vatemperature factor of a high-'temperature elastic fluid in a container Il), which may be a conduit, combustion chamber, or any other type ofjcontainer. The apparatus includes a conduit II` adapted for fiuid connection With the containerl I0, as by means of a fitting I2 secured to the container i9 and a packing gland or nut I3. Anor-ice plate I4 having a high-temperature metering constriction or orifice lila is disposed in the conduit I I or in the fitting I2 which forms an extension thereof and, as illustrated, is in the vicinity of the container I9, specifically at the.. entrance of the conduit ll at the container I. As illustrated, theAfitting I2 has a scooplike extension i211l protruding into the conduit I0 to develop at orifice Ida a pressure which approximates the sum of the static and kinetic pressures of the gas and thus is representative of its-total energy content. At the other end of the conduit II is disposed a fixture I5 secured to the conduit II by a packing nut or gland I6. The fixture I5 isof a generally cup-shaped configuration and includes a low-temperature controlling constriction -or orifice IIa formed in an orifice plate I secured across the open mouth ofthe cup-shaped fixture I5.

As .indicated by dotted lines, the conduit II is preferably of considerable length so that the lowtemperature orice Il'a is remote from the container Ill. If. the conduit Il is of sufiicient length,/itV serves as a heat-exchanging means betweenwthe constrictions I4a and I'Ia for modifying thetemperature ofthe fluid in its flow through'the conduit; it is preferably designed to act as a cooling means for reducing the temperature of the high-temperature fluid from the container II) to a substantially constant value corresponding to the ambient temperature. In certain installations it may be desirable to add coolingfins I Ia to the conduit II to aid in this function.

Attached to the fixture I5 is a valve housing I 8 having a fluid channel Ia communicating With'the orifice Ila and provided with a valve Ib 'disposed therein and communicating'with an outlet channel ISC. In case the static pressure of" elastic fluid in the container Ii) is sufficient to induce a fiovv through the conduit II such as to maintain substantial differential pressures across the orifices Ilia and I'Ia, the outlet I8c of the valve I8 may exhaust directly into the air. However, When the static pressure of the fluid in the container I is relatively low, there may be provided additional means for extracting fiuid from the container I0 through the conduit II so as to maintain substantial differential pressures across the orifices Illa and I'Ia of an aggregate value exceeding the static pressure in the container I0. This means may be in the form of a suction pump I9 having an inlet pipe ISa, connected to the outlet channel I8c of of the valve I8 by means of a packing nut or gland 2U, and having an outlet ISb connecting directly With the atmosphere.

The temperature-responsive apparatus of Fig. 1 further includes means responsive to the differential pressure across the controlling constriction or orifice IIa for determining the fluid mass flow through the conduit II. If the temperature at the orifice IIa, varies substantially, this means includes means for compensating the area of the low-temperature constriction Ila in accordance with variations in the temperature of the fluid at that point. This compensating means may be inthe form ofan adjustable tapered plug 2| extending through the orifice IIa and a thermal element, such as a bi-metallic strip 22, connected to one end of the plug 2! and firmly secured in the fixture I5 to adjust the plug 2| in accordance With variations in temperature. The plug 2| may be disposed to `slide through the central bore of a spider 23 to maintain it accurately in alignment With the aperture IIa. AThe configuration of the tapered plug 2I should be so related to the thermal characteristics of the bi-metallic strip 22 as to maintain substantially constant the ratio of the temperature at the orifice I'Ia to the square of the effective area of such orifice.

The mass-fioW determining means also includes a differential pressure-responsive means connected across the low-temperature constriction Ila and connected directly to the valve Ib to maintain the differential pressure across the low-temperature orifice lia substantially constant. This means may be in the form of a differential-pressure diaphragm 24 mounted in a generally cylindrical chamber 25 in the valve housing I8 and suitably biased by a spring 26. The lower side of the diaphragm 24 is exposed to the low-side pressure at the orifice I'Ia through an opening I8d between the chamber I8a and the chamber 25. The upper face of the diaphragm 24 is exposed to the pressure at the high-pressure side of orifice I'Ia through alconduit 21 communicating with the central chamber of the fixture I5. As illustrated, the conduit 2l is formed by a series of communicating bores with their open ends suitably plugged.

The temperature-responsive apparatus further includes means responsive to the differential pressure across the high-temperature orifice Illa for deriving an effect representative of a temperature factor of the contained fluid. rThis means is illus-.-N

considering certain fundamental.relationships'.

5. It cany be'- shown. by fundamental' thermodynamic relations that: Y

T1=temperature at oricey |`4a T2=temperature at orifice Ha A1=area of orifice Ma A2=area of orifice Ila' P1-Pzzdifferential pressure across orifice Ilm P`21`P3=diiferential pressure across orifice Ila C=constant, including the gas constant R ofthe elasticV fluid and orifice constants of the orifices |4 and Ha.

If. Pz-Pa is maintained. constant, as explained hereinafter, the area A1 of orifice Ma made constanty by construction, and the ratio is maintained constant by the loi-metallic` strip 22, then Equation 2 becomes Returning to the temperature-responsive apparatus of Fig. l,v it is seen that the high-temperature gas flovvingv through the orifice Ida develops ai differential pressure thereacross which is ap-f precise results, these elements are preferably in-v cluded and the configuration of' the plug 2| is so related to the deiiection characteristicV of the bimetallic strip 22 as to maintain the ratio constant'. With this relationship the fluid mass ow through the orice Ila varies only with the differential pressure across the ori''ce'- Ila'. How-- ever, the differential-pressure diaphragm 24 re'- sponsive to the differential fluid' pressure across the orifice Ha' is effective to regulate or control the valve |85 to maintain the differential vpres-- sure across the orifice Ila, substantially constant.V Under these conditions', theI fluid mass flow' through the' system is also maintained substantially constant andthe relationships of Equations 2 and 3 above are satisfied. Under these condi-- tions', the pressure gauge 28, Withv a suitably cali-- Vbrated scale 28j, will indicate directly the tem--r perature of the" fluid in the container IB,

As stated above, if' the pressure of the uid in the container l is' insufficient to maintain an adequate differential pressure across the orifices |'4a and lla to permitaccurate measurement, this differential pressure may be increased'by Equation 2 above are` applicable. the' apparatus of Fig'. l., the area A1 of the highoperation of' the suction pump I9 connectedv to` the outlet of the system. Clearly' thisv suction pump may be of any of the several' types Well known in the art, a Waterv aspirator' type being' Such avpump is thensuitablefor this purpose. .effective to maintain the aggregate value of the differential pressures across the orifices |4a and Vlar substantially greater than the static pressure of? thev fluidvvithin the' containerv |0.

In Fig. 2 is represented schematically a modification ofthe system of Fig. 1, in which corresponding elements are giventhe same reference numerals with an added 100. ment, the dierential pressure element comprising the chamber |25 `and the diaphragm |24 are connected. by means of conduits |2`|a and |211) across the high-temperature orifice |4a and the i diaphragm |24 is connected directly to the Valve |-|8b` in the outlet of the conduit In this instance, the conduit extends an appreciable distance into the container ||0 so that the hightemperature orifice Illiay is Well Within the container ||0 and there is provided heat-exchanging means, such as the fins |||a, connected to the'conduit Within the container |`0 for purposes' hereinafter described.

Further; in the apparatus of Fig. 2 the differential pressure gauge |28 for. developing a temperature-representative effect is connected across the low-temperature orifice ||'|a. In case the static pressure ofthe fluid in the container H0 is: sufcient to maintain substantialv differential pressures across the orifices ||4a and |.||a, the cooling fins' la maybe omitted andthe conduit Hi beyond. the valve ||8b .arranged to discharge directly into; the; air. Alternatively, if the staticv pressure in. the container |||l isv inadequate for.

this. purposer heat-exchanging means such as the fins'` Illa` are provided. and there is further` omission ofthe cooling. fins |||a and the com-.-

pressor |29 and with a static pressure in the container' I l0 sufficient to maintain substantial. differentia'l pressures across the orifices ||4a and fila. through the conduit is from the container |||l to the atmosphere and the relationships of Since as in temperature orifice |.I4a is maintained constant by construction, the'. differential pressure P1-P2 is held constant by the differential pressure regulator |24, |25, and the factor ismainta'ined constant by the compensating' plug |2i and bi-meta'llic strip |22,. Equation 2. be-vr Y comes:

The operation ofV thefapparatus of Fig. 2 with the conditions as assumed is fundamentally' similar to that of Fig. 1 explained above, except that in this instance the high temperature T1 varies inversely With the differential pressure Pz-Ps across the low-temperature orifice ||'|a. However; by a proper calibration of the scale |281' In this embodi- Under these conditions, the flow of fluidV of the pressure gauge |28, that gauge may be made to indicate directly the temperature of the gas in the container ||0.

With the compressor |29 connected and in operation and with the heat exchanger cornprising the fins l la in effect, the flow 'of elastic fluid, specifically air, through the conduit is reversed and, since the fluid mass flow through the orices ||4a and Illa is the same, it can be shown from fundamental thermodynamic relations that:

where the several terms represent the same parameters as those of Equation 2. This equation may be reduced to:

Again, since the several terms of Equation 6 are maintained constant, except T1 and the differential pressure P2-P1, Equation 6 resolves to:

Tr=K (P2-P1) The operation of the apparatus of Fig. 2 With the addition of the heat-exchanging fins Illa and the compressor |29 is essentially similar to that described above, except for the reversal of the direction of flow of fluid through the conduit lll. temperature of the fluid in container IIB varies directly with the differential pressure Pz-Pi across the low-temperature orifice Illa so that, by a proper calibration of the scale |2'8f, the gauge |28 may indicate temperature directly.

The temperature-responsive apparatus of both Figs. l and 2 with the addition of the suction pump I9 and the compressor |29, respectively, are particularly applicable to the measurement of high temperatures of combustion gases in lowpressure apparatus,such as industrial furnaces, the tail cones of jet engines, and other installations where the static pressure is insufficient to maintain adequate differential pressures across the metering and controlling orifices for accurate measurement.

-While there have been described what are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

l. A pneumatic apparatus responsive to a temperature factor of an elastic fluid in a container comprising, a conduit adapted for fluid connection with the container, a metering first constriction in said conduit, a controlling second constriction in'said conduit, heat-exchanging means between said constrictions for modifying the temperature of said fluid, a valve in said conduit, differential-pressure-responsive means connected across said second constriction and connected directly to said valve to maintain the differential pressure across said second constriction substantially constant, and means responsive to the differential fluid pressure across said first constriction for deriving an effect representative of a temperature factor of the contained fluid.

2. A pneumatic apparatus responsive to a tem- In accordance with Equation 7 thev perature factor of an elastic fluid in a container comprising, a conduit adapted for fluid connection With the container, a metering rst orifice in said conduit, 'a controlling second orifice in said conduit, heat-exchanging means between `said orifices for modifying the temperature of said fluid, a valve in said conduit, differential-pressure-responsive means connected across said second orifice and connected directly to said valve to maintain the differential pressure across said second orifice substantially constant, and means responsive to the differential fluid pressure across said first orifice for deriving an effect representative of a temperature factor of the contained fluid.

3. A pneumatic apparatus responsive to a ternperature factor of a high-temperature elastic fluid in a container comprising, a conduit adapted for fluid connection with the container, a metering first constriction in said conduit, a controlling second constriction in said conduit, cooling means between said constrictions for reducing the temperature of said fluid, a Valve in said conduit, differential-pressure#responsive means connected across said second'constriction and connected directly to said valve to maintain the differential pressure across said second constriction substantially constant, and means responsive to the differential fluid pressure across said first constriction for deriving an effect representative of a temperature factor of the contained fluid.

4. A pneumatic apparatus responsive to a temperature factor of a high-temperature elastic fluid in a container comprising, a conduit adapted for fluid connection with the container, a high-temperature constriction in said conduit in the vicinity of the container, a low-temperature constriction in said conduit remote from the container, cooling means between said constrictions for reducing the temperature of said fluid, a valve in said conduit, differential-pressure-responsive means connected across one of said constrictions and connected directly to said valve to maintain the differential pressure across said one of said constrictions substantially constant, and means responsive to the differential fluid pressure across the other of said constrictions for deriving an effect representative of a temperature factor of the contained fluid.

5. A pneumatic apparatus responsive to a temperature factor of a high-temperature elastic fluid in a container comprising, a conduit adapted for fluid connection with the container,

a metering first constriction in said conduit, a controlling second constriction in said conduit, cooling means between said constrictions for reducing the temperature of said fluid to a substantially constant value, a valve in said conduit, differential-pressure-responsive means connected across said second constriction and connected directly to said valve to maintain the differential pressure across said second constriction substantially constant, and means responsive to the differential fluid pressure across said first constriction for deriving an effect representative of a temperature factor of the contained fluid.

6. A pneumatic apparatus responsive to a temperature factor of a high-temperature elastic fluid in a container comprising, a conduit adapted for fluid connection with the container, a high-temperature constriction in said conduit in the vicinity of the container, a low-temperature constriction in said conduit remote from the container, coolingmeans between said constrictions forreducing the temperature of said fluid,

means responsive to the'fluid temperature-at said "low-temperature constriction for compensating conduit, differential-pressure-responsive means connected across one of said constrictions and connected directly to vsaid Valve to maintain the differential pressure across said one of said constrictions substantially constant, and means responsive to the differential fluid pressure across the other of said constrictions for deriving an effect representative of a temperature factor of the contained fluid.

'7. A pneumatic apparatus responsive to a ternperature factor of a high-temperature elastic uid in a container comprising, a conduit adapted for fluid connection With the container, a high-temperature constrictionr in said conduit adjacent the end thereof adapted for connection to the container, a low-temperature constriction in said conduit remote from said high-temperature constriction, cooling means between said constrictions for reducing the temperature of said fluid, an adjustable tapered plug for said lowtemperature constriction, a thermal element connected to adjust said plug to maintain substantially constant the ratio of the temperature thereat to the square of the effectivelarea of the associated constriction, a valve in said conduit, differential-pressure-responsive means connected across one of said constrictions and connected directly to said valve to maintain the differential pressure across said one of said constrictions substantially constant, and means responsive to the diiferential fluid pressure across the other of said constrictions for deriving an effect representative of a temperature factor of the contained uid.

8. A pneumatic apparatus responsive to a temperature factor of an elastic fluid in a container comprising, a conduit adapted for nuid connection with the container, a metering first constriction in said conduit, a controlling second constriction in said conduit, heat-exchanging means between said constrictions for modifying the' temperature of said iiuid, a Valve in said conduit, differential-pressure-responsive means connected across said second constriction and connected directly to said valve to maintain the diiferential pressure across said second constriction substantially constant, and a differential-pressure gauge connected across said first constriction and calibrated in terms of temperature.

9. A pneumatic apparatus responsive to a tcmperature factor of a high-temperature elastic fluid in a container comprising, a conduit adapted for fluid connection with the container, a hightemperature constriction in said conduit adjacent the end thereof adapted for connection to the container, a low-temperature constriction in said conduit remote from said high-temperature constriction, cooling means between said constrictions for reducing the temperature of said fluid, a valve in said conduit, differential-pressureresponsive means connected across said low-temperature constriction and connected directly to said valve to maintain the diiferential pressure across said low-temperature constriction substantially constant, and means responsive to the differential fluid pressure across said high-temperature constriction for deriving an effect representative of a temperature factor of the contained fluid.

l0. A pneumatic apparatus responsive to a temperature factor of a high-temperature elastic fluid in a container comprising, a conduit adapted for fluid connection with the container, a hightemperature constriction in said conduit adjacent the end 'thereof adapted for connection to the container, a low-temperature constrictionl in said conduit remote from the container, cooling means between said constrictions for reducing the temperature of said ii-uid, a valve in said conduit,

differential-pressure-responsive means connected across said high-temperature constriction and connected directly to said valve to maintainV the differential pressure acrosssaid high-temperature constriction .substantially constant, and means responsive to the diiferential uid pressure across said low-temperature constriction for deriving an effect representative of a temperature factor of the contained fluid.

ll. A pneumatic apparatus responsive to'a tem-` perature factor of an elastic iiuid in a container comprising, a conduit adapted for uid connection with the container, a metering first constriction in said conduit, a controlling second constriction in said conduit, means for inducing the flow of elastic fluid through said conduit to maintain substantial differential pressures across said constrictions, heat-exchanging means between said constrictions for modifying the temperature of said fluid, a valve in said conduit, differentialpressure-responsive means connected across said second constriction and connected directly to said valve to maintain the differential pressure across said second constriction substantially constant, and means responsive to the differential fluid pressure across said rst constriction for deriving an effect representative of a temperature factor of the contained uid. Q

l2. A. pneumatic apparatus responsive to a temperature factor of an elastic uid in a container comprising, a conduit adapted for fluid connection with the container, a metering first constriction in said conduit, a controlling second constriction in said conduit, means for extracting fluid through said conduit to maintain differential pressures across said constrictions having an aggregate value exceeding the static pressure in the container, heat-exchanging means between said constricticns for modifying the temperature of said fluid, a valve in said conduit, differentialpressure-responsive means connected across said second constriction and connected directly to said valve to maintain the differential pressure across said second constriction substantially constant, and means responsive to the differential fluid pressure across said rst constriction for deriving an effect representative of a temperature factor of the contained fluid.

13. A pneumatic apparatus responsive to a temperature factor of an elastic fluid in a container comprising, a conduit adapted for uid connection with the container, a metering rst constriction in said conduit, a controlling second constriction in said conduit, means for forcing air through said conduit into said container to maintain substantial differential pressures across said constrictions, heat-exchanging means connected to said conduit and adapted to be disposed in the container for changing the temperature of the conduit air. substantially to that of the fluid in the container, a valve in said conduit, differentialpressure-responsive means connected across said second constriction and connected directly tosaid valve to' maintain the differentialpressure across said second constriction substantially constant, and means responsive to the differential fluid pressure across said first constriction for deriving 11 an effect representative of a temperature factor Number of the contained fluid. 554,323 DAVID W. MOORE, JR. 773,684 ALFRED G. NASH. .1,630,307 5 2,258,878 H REFERENCES CITED 2,463,416 The fyllowing references are of record in the le of this patent:

v Number UNITED STATES PATENTS lo 237,827 Number Name Date Re. 11,413 Uehling et al Apr. 177, 1894 Name Date Uehling et a1 Feb. 11, 1896 Speller Nov. 1, 1904 Norwood et a1 May 31, 1927 Bassler Oct. 14, 1941 Stresen-Reuter Apr. 26, 1949 FOREIGN PATENTS Country Date Great Britain Aug. 6, 1925 

